Dyslexia and Reading Ability Predict Sequence Learning Impairments

Dyslexia is a learning disability characterized by deficits in word recognition and spelling, and previous research suggests that people with dyslexia may also show deficits in sequence learning, a process important for literacy acquisition. However, results from previous studies have been mixed, with some suggesting that individuals with dyslexia show impairments relative to controls and others suggesting that they do not. Furthermore, the sequence learning tasks used in other studies are often motor sequencing tasks, and so it is unclear whether previous studies reflect true sequence learning deficits or merely motor-based learning impairments. To measure sequence-specific learning in the present study, 39 college-aged students (19 dyslexic, 20 non-dyslexic) completed a non-motor feedback-based task with sequencing and non-sequencing components. Participants with dyslexia made significantly more sequencing errors, but were not impaired on the other non-sequencing phases, compared to control subjects. Participants also completed a battery of neuropsychological tasks to assess reading and spelling ability, and results showed that reading ability of nonsense words, which reflects phonological processing ability, was a significant mediator of the relationship between dyslexia status and sequencing performance. These findings not only support previous literature suggesting that individuals with dyslexia show sequence learning impairments, but also suggest that reading ability may play an important role in sequence learning in healthy adults of all ages.